东北亚的新仙女木和全新世气候演变的初步证据── 一个湖泊岩心的古环境变化的同位素和磁性记录

内蒙古合同察汗淖碱湖的磁化率和稳定同位素资料的初步证据表明,在东北亚也经历了新仙女木（ＹｏｕｎｇｅｒＤｒｙａｓ）寒冷事件。此外,９０００～６０００ａＢＰ的潮湿气候环境可能是由于季风活动加剧所致,随后,一个逐渐干化的气候条件一直延续到现在。     

20 My of nitrogen fixation during deposition of mid-Cretaceous black shales on the Demerara Rise,equatorial Atlantic Ocean

Thick sequences of dark colored, organic carbon rich, finely laminated Santonian–Cenomanian claystones and homogeneous Albian siltstones were recovered from Ocean Drilling Program Sites 1257, 1258 and 1260 on the Demerara Rise in the western equatorial Atlantic Ocean. Total organic carbon (TOC) concentrations vary from 2 to over 20 wt% in the sequences of “black shales” that were deposited over a period of ～20 million years. Similarly long periods of elevated marine productivity implied by the high TOC concentrations are uncommon in the geological record and must have required unusual paleoceanographic conditions. The importance of nitrogen fixing bacteria to sustaining the amplified export production of organic matter is indicated by δ¹⁵N values that remain between ?4‰ and 0‰, a range that is notably less positive than the average of +5‰ for modern ocean sediments. Although containing mostly marine organic matter, the black shales have TOC/TN molar ratios between 20 and 40 that mimic those of land plant organic matter. The anomalously large TOC/TN ratios suggest selective organic matter degradation, probably associated with low oxygen conditions in the water column, that favored preservation of nitrogen poor forms of organic matter relative to nitrogen rich components. Deposition of black shales on the Demerara Rise was likely a consequence of the mid-Cretaceous warm and wet greenhouse climate that strengthened thermohaline stratification of this part of the Atlantic Ocean, which in turn encouraged bacterial nitrogen fixation, enhanced primary production, magnified organic matter export, and ultimately established anoxic conditions at the seafloor that improved preservation of organic matter for much of the 20 My period represented by these thick sequences.     

Impact of methane seeps on the local carbon‐isotope record: a case study from a Late Jurassic hemipelagic section

An Oxfordian (Late Jurassic) hemipelagic succession from Beauvoisin (SE France) contains a pronounced, short‐lived negative excursion in the bulk‐carbonate carbon‐isotope record, with an amplitude of 4‰. It was shown previously that the Beauvoisin paleoenvironment was impacted by hydrocarbon seepage. New isotopic data corroborate that methane was a significant constituent of these hydrocarbons. The negative excursion was caused by transient enhanced precipitation of ¹³C‐depleted carbonate, mediated by anaerobic oxidation of methane. Despite its local diagenetic origin, the Beauvoisin excursion is similar in shape and duration to globally recognized negative C‐isotope excursions that have been related to catastrophic, massive dissociation of methane hydrate. Shape and duration of negative excursions therefore cannot be used as an argument when determining their origin if they have not been shown to represent a global perturbation of the carbon cycle.     

Carte geografiche secondo il modello della membrana elastica

Riassunto Quando una membrana elastica ed isotropa che riveste parzialmente una sfera viene distesa su un piano, la rete dei meridiani e paralleli stampata sulla membrana stessa si deforma secondo il principio della minima energia. L'Autore illustra con alcuni esempi la possibilità di ottenere buone proiezioni cartografiche fruendo del principio medesimo.

---

Summary Whenever an elastic and isotropic diaphragm partially coating a sphere is spread on a plane, the net of the meridians and parallels loses the proper shape according to the principle of the lowest energy. The Author explains through some examples how to get cartographic projections by using the same principle.

     

Nuovo metodo di registrazione dello stato del mare e primi risultati ottenuti a Genova

Riassunto Viene descritto ed illustrato un nuovo procedimento di registrazione del moto ondoso marino, il quale consiste sostanzialmente nel trasformare l'escursione verticale che subisce la superficie del mare nella compressione o dilatazione di una massa d'aria sovrastante racchiusa in un tubo verticale munito superiormente di opportuna membrana sensibile. Un tale apparecchio, installato a Prà (Genova) dal-l'Istituto Geofisico dell'Università di Genova, funziona con successo da alcuni mesi. Segue un esame dei primi risultati ivi conseguiti, dal quale appare l'importanza del passaggio dei fronti freddi sul moto ondoso del mare.

---

Summary A new method for the recording of sea-wave motion is described and explained. It consists in having the vertical movement of the sea surface transformed into compression or expansion of a volume of air enclosed in a tube which is carrying on its upper part a sensitive membrane. This self-recording instrument, set up at Prà (Genoa) by the Istituto Geofisico dell'Università di Genova is functioning since several months already without giving rise to objections. Some first results obtained up now are also examided, from which it appears the importance of the passage of cold fronts.

---

Zusammenfassung Es wird ein neues Verfahren für die Registrierung der Meereswellenbewegung beschrieben und erläutert. Es besteht darin, dass der vertikale Gang der Meeresoberfläche umgewandelt wird in Kompression oder Expansion einer in einem Rohre befindlichen Luftmasse, welche am oberen Teil von einer empfindlichen Membran geschlossen ist. Dieser Gerät, vom Istituto Geofisico dell'Università di Genova in Prà (Genua) aufgestellt, arbeitet bereits seit einigen Monaten einwandfrei. Einige vorläufige Ergebnisse werden dann erläutert, wofür auf die Bedeutung des Durchganges von Kaltfronten hingewiesen wird.

     

Nile floods recorded in deep Mediterranean sediments

Clastic mud beds rich in continental organic matter are observed recurrently in the Nile deep-sea turbidite system. They formed during flooding periods of the river similar to those that induce sapropel formation and occurred during periods of increased density stratification of the eastern Mediterranean. The very fine-grained flood deposits are intercalated within pelagic sediments, sapropels and Bouma-type turbidites. These flood deposits form by the successive reconcentrations of surface (hypopycnal) plumes by convective sedimentation, which in turn generate a fine-grained low-energy hyperpycnal flow. Sea-level high stands seem also to favor hypopycnal plume formation and increase clastic mud bed formation. Consequently, these muddy clastic beds provide a direct link between deep-marine sedimentary records and continental climatic change through flood frequency and magnitude.     

Seasonal variability of soil phosphate stable oxygen isotopes in rainfall manipulation experiments

Phosphorus (P) availability limits productivity in many ecosystems worldwide. As a result, improved understanding of P cycling through soil and plants is much desirable. The use of the oxygen isotopes associated to phosphate can be used to study the cycle of P in terrestrial systems. However, changes with time in the oxygen isotopes associated to available P have not yet been evaluated under field conditions. Here we present the variations in available-P oxygen isotopes, based on resin extractions, in a semi-arid site that included plots in which the amount of rainfall reaching the soil was modified. In addition, the oxygen isotopes in the less dynamic fraction which is extractable by HCl, were also measured. The δ¹⁸O of the HCl-extractable phosphate shows no seasonal pattern and corresponds to the average value of the available phosphate of 16.5‰. This value is in the expected range for equilibration with soil water at the prevailing temperatures in the site. The δ¹⁸O values of resin-extractable P showed a range of 14.5-19.1‰ (SMOW), and evidence of seasonal variability, as well as variability induced by rainfall manipulation experiments. We present a framework for analyzing the isotopic ratios in soil phosphate and explain the variability as mainly driven by phosphate equilibration with soil water, and by the isotopic effects associated with extracellular mineralization. Additional isotopic effects result from fractionation in uptake, and the input to the soil of phosphate equilibrated in leaves. These results suggest that the δ¹⁸O of resin-extractable P is an interesting marker for the rate of biological P transformations in soil systems.     

Early diagenesis in rapidly accumulating sediments on the Alboran slope, ODP site 976

The oxidation and reduction that occur during early diagenesis of sediments has been studied in the interstitial waters of a rapidly accumulating sedimentary sequence from the Mediterranean margin of Spain. A series of reactions that are mediated by progressively lower free energy derived from oxidation of organic matter is evident in the sedimentary sequence. Iron and manganese are rapidly reduced. Phosphate and alkalinity maxima at a subbottom depth of 15?m indicate maximal organic matter degradation. Methane first appears at ～20?m subbottom after sulfate is depleted, and its concentrations quickly climb.     

Le barovariographe comme appareil de sondage aérologique

Summary First, the theory of the barovariograph, the deductions from which have also been confirmed by experiments, is presented with some improvements. Then there follows a concise illustration of the various possibilities of applying the instrument for the disclosure of aerological phenomena existing over a given locality.

---

Zusammenfassung Zunächst wird, mit einigen Erweiterungen, die Theorie des Barovariographen dargelegt, deren Ableitungen auch experimentell bestätigt wurden. Dann folgt eine kurze Erläuterung der verschiedenen Anwendungsmöglichkeiten des Instrumentes für die Registrierung gewisser aerologischer Erscheinungen über einem Ort.

---

Riasunto Dapprima viene esposta con alcuni perfezionamenti la teoria del barovariografo, le cui deduzioni sono state confermate anche sperimentalmente. Segue una illustrazione succinta delle varie possibilità applicative dello strumento per la rilevazione dei fenomeni aerologici sovrastanti una località determinata.

---

---

Communication présentée à l'Association Internationale de Météorologie, IXe Assemblée Générale de l'UGGI, Bruxelles, Séance du 24 Août 1951.     

Sull'idrologia del Foehn

Riassunto Per alcuni casi diFöhn delle Alpi Italiane, interessanti il Piemonte e la Lombardia, sono state esaminate le variazioni dei deflussi nei giorni in cui soffiava tale vento nonchè in quelli adiacenti, trovando che di regola, quando non intervengono precipitazioni od altri fattori, ilFöhn provoca una diminuzione netta delle portate, che può raggiungere e superare il 10% e che si esplica con relativa prontezza. Si spiega tale riduzione con la forte evaporazione causata dalFöhn.

---

Summary Researches have been undertaken on the influence of the Föhn in the italian Alps, regarding the runoff-variations. The Föhn causes as a rule a decrease of the runoff, which, in absence of precipitation, can reach or exceed 10%. It can be explained by the strong evaporation during the Föhn.

---

Zusammenfassung Anhand einiger Föhnfälle in den italienischen Alpen wurde der Einfluss des Föhns auf die Aenderungen der Abflussmenge untersucht. Wenn empfindliche Niederschläge oder andere Faktoren nicht vorkommen, verursacht in der Regel der Föhn eine Abnahme der Abflussmenge, die 10% erreichen oder sogar überschreiten kann. Die Erklärung ist in der starken Verdunstung während des Föhns zu suchen.